A 21-year-old Queens beauty lost control of her car and fatally struck a man walking along the sidewalk – before hitting a tree and killing herself, cops said yesterday.

Devastated family, colleagues and police last night were at a loss to explain how Melissa Carro suddenly lost control of her car as drove to work east on Marcus Avenue, in north New Hyde Park on Long Island, about 8.30 a.m.

Tyrone Singletary, 30, of North Bellport, was killed instantly when Carro’s silver Honda flew onto the curb and struck him.